refactor: simple_engine (#280)

Author: milindsrivastava1997

asap-common/dependencies/rs/sql_utilities/src/ast_matching/sqlpattern_matcher.rs

@@ -71,6 +71,17 @@ impl SQLQuery {
     pub fn is_valid(&self) -> bool {
         self.error.is_none()
     }
+
+    /// The outer (spatial / single) query's data — always `query_data[0]`.
+    pub fn outer_data(&self) -> Option<&SQLQueryData> {
+        self.query_data.first()
+    }
+
+    /// The inner (temporal) query's data for nested queries — always `query_data[1]`.
+    /// Only valid for `OneTemporalOneSpatial` patterns.
+    pub fn inner_data(&self) -> Option<&SQLQueryData> {
+        self.query_data.get(1)
+    }
 }
 
 pub struct SQLPatternMatcher {

asap-query-engine/src/data_model/traits.rs

@@ -30,6 +30,20 @@ pub trait AggregateCore: SerializableToSink + Send + Sync {
 
     /// Get all keys stored in this accumulator
     fn get_keys(&self) -> Option<Vec<KeyByLabelValues>>;
+
+    /// Dispatch a statistic query without downcasting.
+    ///
+    /// Replaces the 12-arm `match get_accumulator_type()` in the engine.
+    /// Single-subpopulation types ignore `key`; multiple-subpopulation types
+    /// require it and return `Err` when it is `None`.
+    /// Special cases (DeltaSetAggregator, SetAggregator) fall back to a
+    /// cardinality value when `key` is `None`.
+    fn query_statistic(
+        &self,
+        statistic: Statistic,
+        key: &Option<KeyByLabelValues>,
+        query_kwargs: &HashMap<String, String>,
+    ) -> Result<f64, Box<dyn std::error::Error + Send + Sync>>;
 }
 
 /// Trait for accumulators that support a single subpopulation